Abstract

Background

Following claims that some plants have antimicrobial activities against infectious
microbes, the in vitro antimicrobial activities of different solvent fractions of ethanolic extract of Cryptolepis sanguinolenta were evaluated against eight standard bacteria and clinical isolates.

Methods

The solvent partitioning protocol involving ethanol, petroleum ether, chloroform,
ethyl acetate and water, was used to extract various fractions of dried pulverized
Cryptolepis sanguinolenta roots. Qualitative phyto-constituents screening was performed on the ethanol extract,
chloroform fraction and the water fraction. The Kirby Bauer disk diffusion method
was employed to ascertain the antibiogram of the test organisms while the agar diffusion
method was used to investigate the antimicrobial properties of the crude plant extracts.
The microplate dilution method aided in finding the MICs while the MBCs were obtained
by the method of Nester and friends. The SPSS 16.0 version was used to analyze the
percentages of inhibitions and bactericidal activities.

Results

The phytochemical screening revealed the presence of alkaloids, reducing sugars, polyuronides,
anthocyanosides and triterpenes. The ethanol extract inhibited 5 out of 8 (62.5%)
of the standard organisms and 6 out of 8 (75%) clinical isolates. The petroleum ether
fraction inhibited 4 out of 8 (50%) of the standard microbes and 1 out of 8 (12.5%)
clinical isolates. It was also observed that the chloroform fraction inhibited the
growth of all the organisms (100%). Average inhibition zones of 14.0 ± 1.0 mm to 24.67 ± 0.58 mm
was seen in the ethyl acetate fraction which halted the growth of 3 (37.5%) of the
standard organisms. Inhibition of 7 (87.5%) of standard strains and 6 (75%) of clinical
isolates were observed in the water fraction. The chloroform fraction exhibited bactericidal
activity against all the test organisms while the remaining fractions showed varying
degrees of bacteriostatic activity.

Conclusion

The study confirmed that fractions of Cryptolepis sanguinolenta have antimicrobial activity. The chloroform fraction had the highest activity, followed
by water, ethanol, petroleum ether and ethyl acetate respectively. Only the chloroform
fraction exhibited bactericidal activity and further investigations are needed to
ascertain its safety and prospects of drug development.